Sample inspection apparatus and sample inspection method

Abstract

A sample detection apparatus includes a light radiation unit, having an illumination lens and an objective lens, for radiating light on a sample on which a pattern relating to fabrication of a semiconductor device is formed. A light receiving unit detects a light transmission image of the pattern on the sample on which the light has been radiated by the light radiation unit. A determination unit determines a presence/absence of a defect of the pattern obtained by the light receiving unit with reference data relating to the pattern, and a control unit controls a ratio σ of a numerical aperture of the objective lens, in accordance with a type of the pattern.

What is claimed is: 
     
       1. A sample inspection apparatus comprising: a light source radiating light on a sample on which a pattern relating to fabrication of a semiconductor device is formed;   an illumination lens provided between said light source and said sample for illuminating light on said sample;   light receiving means for detecting a light transmission image of the pattern on the sample on which the light has been radiated by said light source;   an objective lens, provided between said sample and said light receiving means, focusing an image of the pattern on the sample onto said light receiving means;   determination means for determining a presence/absence of a defect of the pattern by comparing measurement data corresponding to the light transmission image of the pattern obtained by said light receiving means with reference data relating to said pattern; and   control means for controlling a ratio σ of a numerical aperture of said illumination lens to a numerical aperture of said objective lens, in accordance with a type of said pattern.   
     
     
       2. The sample inspection apparatus according to claim 1, wherein the reference data in said determination means is design data of said pattern. 
     
     
       3. The sample inspection apparatus according to claim 1, wherein the reference data in said determination means is measurement data of a pattern different from the pattern to be inspected. 
     
     
       4. The sample inspection apparatus according to claim 1, wherein the type of the pattern in said control means is determined by the type of shape of an edge portion of the pattern. 
     
     
       5. The sample inspection apparatus according to claim 1, wherein the ratio σ of the numerical aperture of said illumination lens to the numerical aperture of said objective lens in said control means is controlled by an optical element including an optical filter and an aperture. 
     
     
       6. The sample inspection apparatus according to claim 5, wherein said optical filter and said aperture in said optical element are constituted as one body. 
     
     
       7. The sample inspection apparatus according to claim 1, wherein the ratio σ of the numerical aperture of said illumination lens to the numerical aperture of said objective lens in said control means is controlled by a plurality of optical elements including an optical filter and an aperture and having different optical characteristics, and a mechanism for selecting one of said optical elements. 
     
     
       8. The sample inspection apparatus according to claim 7, wherein said mechanism includes a jig for removably fixing said plurality of optical elements. 
     
     
       9. The sample inspection apparatus according to claim 7, wherein said mechanism includes means for selecting one of said plurality of optical elements based on the type of the pattern. 
     
     
       10. A sample inspection apparatus comprising: a light source radiating light on a sample on which a pattern relating to fabrication of a semiconductor device is formed;   an illumination lens provided between said light source and said sample for illuminating light on said sample;   light receiving means for detecting a light transmission image of the pattern on the sample on which the light has been radiated by said light source;   an objective lens, provided between said sample and said light receiving means, focusing an image of the pattern on the sample onto said light receiving means;   determination means for determining a presence/absence of a defect of the pattern by comparing measurement data corresponding to the light transmission image of the pattern obtained by said light receiving means with reference data relating to said pattern; and   control means for controlling said light source such that a ratio σ of a numerical aperture of said illumination lens to a numerical aperture of said objective lens is varied and an output of said light receiving means is substantially constant when the ratio σ of the numerical aperture is varied.   
     
     
       11. The sample inspection apparatus according to claim 10, wherein said control means is operated in accordance with a type of the pattern to be inspected. 
     
     
       12. The sample inspection apparatus according to claim 11, wherein the type of the pattern in said control means is determined by the type of shape of an edge portion of the pattern. 
     
     
       13. The sample inspection apparatus according to claim 10, wherein the reference data in said determination means is design data of said pattern. 
     
     
       14. The sample inspection apparatus according to claim 10, wherein the reference data in said determination means is measurement data of a pattern different from the pattern to be inspected. 
     
     
       15. The sample inspection apparatus according to claim 11, wherein said control means includes an aperture for varying the ratio σ of the numerical aperture of said illumination lens to the numerical aperture of said objective lens. 
     
     
       16. The sample inspection apparatus according to claim 11, wherein said control means includes means for varying light transmissivity. 
     
     
       17. The sample inspection apparatus according to claim 11, wherein said control means includes an optical filter for making an output of said light receiving means substantially constant when the ratio σ of the numerical aperture is varied. 
     
     
       18. The sample inspection apparatus according to claim 11, wherein said control means includes an aperture for varying the ratio σ of the numerical aperture of said illumination lens to the numerical aperture of said objective lens, and an optical filter for making an output of said light receiving means substantially constant when the ratio σ of the numerical aperture is varied. 
     
     
       19. The sample inspection apparatus according to claim 18, wherein said aperture and said optical filter are constituted as one body. 
     
     
       20. The sample inspection apparatus according to claim 11, wherein said control means includes a plurality of optical elements including an optical filter and an aperture and having different optical characteristics, and a mechanism for selecting one of said optical elements. 
     
     
       21. The sample inspection apparatus according to claim 20, wherein said mechanism includes a jig for removably fixing said plurality of optical elements. 
     
     
       22. The sample inspection apparatus according to claim 21, wherein said mechanism includes means for selecting one of said plurality of optical elements based on the type of the pattern to be inspected. 
     
     
       23. A sample inspection method comprising the steps of: radiating light on a sample, on which a pattern relating to fabrication of a semiconductor device is form via an illumination lens;   receiving the light for detecting a light transmission image of the pattern on the sample via an objective lens on which the light has been radiated in said light radiation step;   focusing an image of the pattern on said sample;   determining the presence/absence of a defect of the pattern by comparing measurement data corresponding to the light transmission image of the pattern obtained in said light receiving step with reference data relating to said pattern; and   controlling the ratio σ of the numerical aperture of said illumination lens to the numerical aperture of said objective lens, in accordance with type of said pattern.   
     
     
       24. The sample inspection method according to claim 23, wherein said ratio σ is 1<σ≦0.65. 
     
     
       25. A sample inspection method comprising the steps of: radiating light on a sample, on which a pattern relating to fabrication of a semiconductor device is formed via an illumination lens;   receiving the light for detecting a light transmission image of the pattern on the sample via an objective lens on which the light has been radiated in said light radiation step;   focusing an image of the pattern on said sample;   determining a presence/absence of a defect of the pattern by comparing measurement data corresponding to the light transmission image of the pattern obtained in said light receiving step with reference data relating to said pattern; and   controlling said light radiation step, thereby executing an operation of varying a ratio σ of a numerical aperture of said illumination lens to a numerical aperture of said objective lens, and an operation of making an output in said light receiving step substantially constant even when the ratio σ of the numerical aperture is varied.   
     
     
       26. The sample inspection method according to claim 25, wherein said ratio σ is 1 <σ≦0.65. 
     
     
       27. A sample inspection method wherein light is radiated on a sample on which a pattern relating to fabrication of a semiconductor device is formed, via an optical system having an illumination lens and an objective lens both having specified numerical apertures, thereby detecting a light transmission image of said pattern by light receiving means, and a presence/absence of a defect of the pattern is determined by comparing measurement data corresponding to the light transmission image of the pattern obtained by said light receiving means with reference data relating to said pattern, said method comprising the steps of: detecting a signal wave dull in said measurement data at an edge portion of the pattern; and   compensating the wave dull detected in said detecting step by controlling a ratio σ of the numerical aperture said illumination lens to the numerical aperture of said objective lens.   
     
     
       28. The sample inspection method according to claim 27, wherein said ratio σ is 1<σ≦0.65.